I. Field of the Invention
The invention relates to an apparatus for dynamically mixing and dispensing multi-component fluids and, more particularly, it concerns a dynamic mixing and dispensing gun adapted to be used with systems in which two or more fluid components, separately stored in dispensing vessels, are mixed and dispensed as a settable sealant, wherein the mixing occurs in a mixing chamber liner with a mixing paddle which constitutes a disposable chamber and paddle combination that can eliminate hours of cleaning associated with non-disposable components.
II. Description of the Related Art
U.S. Pat. Nos. 4,762,253 and 4,603,813 disclose dispensing guns in which separate fluid components are fed individually to the gun, passed separately through controlled valve ports and brought into contact with each other only upon reaching a mixing chamber of a nozzle from which the mixed components are discharged. The nozzles for the gun are designed to be replaceable and disposable in order to avoid the necessity of cleaning any part of the gun which comes into contact with mixed, as distinguished from separate, fluid components. The nozzles are retained on the gun body with relative rigidity, without leakage of fluid components between the gun body and the nozzle, and yet in a manner to facilitate nozzle removal and replacement. Each of these patents includes a stationary, helically configured mixing guide or baffle positioned within the mixing chamber for imparting a controlled, helical, swirling or mixing action to the liquid components entering the chamber from the inlet ports, and to increase the amount of time within the mixing chamber. This type of stationary, baffle configuration is satisfactory for chemicals which are easily mixed, and for chemicals which expand after mixing due to the presence or formation of a blowing agent, such as that present in foam products. However, this stationary, baffle configuration is unsatisfactory where more vigorous dynamic mixing is required.
U.S. Pat. No. 3,622,126 discloses a spray gun for mixing and applying a two-part mixture, such as a plastic and a catalyst. The spray gun has a mixing chamber that receives at one end thereof controlled or metered amounts of the two ingredients of the mixture from their respective sources of supply and discharges the mixture from an outlet at the other end. A mixing rotor is provided with mixing blades extending radially from a central body. The rotor is mounted in the chamber and is rotated continuously while the gun is in use. The upstream sides of the rotor blades are inclined relative to their respective planes of rotation to exert an axial flow, impeller-type action on the contents of the chamber, thereby creating a high-degree of turbulence within the chamber that tends to propel the contents back away from the chamber outlet. After each period of use, it is essential to thoroughly clean the gun of the catalyzed plastic. This is accomplished by shutting off the flow of plastic and catalyst to the mixing chamber and supplying a suitable pressurized cleaning solvent, such as acetone, to the chamber. With the acetone in the chamber, the rotor is rotatively driven to create an extreme turbulence and flushing of the mixed plastic and catalyst from the mixing chamber. The rotor tends to drive the acetone fluid axially inward, flushing the mixed plastic and catalyst from the chamber at the outlets of the passages, assuring that all of the mixed contents are flushed out of the chamber. This type of dynamic mixing and dispensing gun suffers from the disadvantage of having to be flushed with a suitable solvent for cleaning the mixing chamber after use. The use of solvents for cleaning is time consuming, expensive and creates solvent waste disposal problems.